The present invention relates to a method for operating a gasification burner/heating boiler installation.
In conventional heating boiler installations, oil burners are used on a large scale. Conventional oil burners of medium rating atomize the heating or fuel oil by means of a nozzle and burn it with excess air in order to minimize the development of soot. However, the atomizing burner output is difficult to control continuously, and then only in a closely defined range. For this reason, atomizing burners for heating boiler installations are operated intermittently so that the average of the output corresponds to the heat demand.
In the operation of conventional atomizing burners, the oil mass flow is given by the viscosity of the heating oil, the cross section of the atomizer nozzle and the oil pressure. The air mass flow is adjusted only when starting the operation and for servicing to the instantaneous value of pressure and temperature of the suction air as a volume flow, and specifically, to so high a value of air excess (.lambda..iota.1.2 to 1.5) that the CO content and the soot number of the exhaust gas do not exceed predetermined limits. Control of the mass ratio between the fuel, i.e., the oil, and air does not take place, so that the combustion air number changes with the viscosity as well as with the H/C and the S/C ratio of the fuel and with the temperature, the pressure and the water vapor content of the drawn-in combustion air in an uncontrolled manner. Along with this uncontrolled change, however, goes the danger of soot formation and a variation of the efficiency.
From U.S. Pat. No. 4,230,443, a continuously controlled gasification or vaporizing burner is known. This burner is based on the principle of two-stage combustion where, in the first stage, heating oil is gasified in a catalytic reactor by partial oxidation with air (gasification or primary air) at air numbers between 0.05 and 0.2 and preferably at about 0.1. The so-obtained product gas, the so-called fuel gas, is then burned stoichiometrically with the remaining air (combustion or secondary air), high combustion temperatures being obtained. The composition of the exhaust gas corresponds substantially to that of the thermodynamic equilibrium at the combustion temperature.